Embodiments of the invention relate to a semiconductor device and a method of fabricating the semiconductor device.
Trench metal oxide semiconductor (MOS) transistors differ from MOS transistors in that channels of the trench MOS transistors are formed in a vertical direction. Channels of more conventional MOS transistors are formed in a horizontal direction. The trench MOS transistor includes a vertical channel and a drain formed in a backside of a wafer as an output region.
As compared with more conventional MOS transistors, the trench MOS transistors are suitable for high-current and high-voltage operations using a small area. To apply a high voltage to the trench MOS transistor, it is necessary to form a lightly doped drain region (a drift region) in a sufficiently large length.
Since electrons move vertically in a trench MOS transistor, a lightly doped drain region can be vertically formed to increase a withstand voltage without increasing the area of a chip by adjusting a vertical doping profile. Therefore, high withstand-voltage and high-current operation can be possible using a small area. However, the structure of a trench MOS transistor may be changed to form the trench MOS transistor on a chip as a CMOS transistor.